Technical Field
The present disclosure relates to a method for alleviating radiation injury with a composition containing isorhamnetin-3-O-β-D-glucoside.
Background Information
Radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. In general, radiation is classified as: (1) ionizing radiation, which refers to high-energy electromagnetic waves (e.g., X-rays and gamma rays) or particles (e.g., alpha particles, beta particles and neutrons) capable of ionizing atoms or molecules; and (2) non-ionizing radiation, which refers to low-energy electromagnetic waves (e.g., visible light, infrared, ultraviolet and microwaves) not capable of ionizing atoms or molecules. Radiation exposure to organisms can lead to DNA damage, thereby causing gene mutation and inducing apoptosis and cell death, and finally resulting in radiation injury (including ionizing radiation injury and non-ionizing radiation injury).
Ionizing radiation injury may be classified into the following three categories based on the degree of radiation exposure:    (1) acute radiation syndrome (ARS), also known as radiation poisoning and radiation sickness, which is caused when the entire human body is exposed to ionizing radiation over a short period of time (e.g., within 24 hours), and whose symptoms may be classified as related to the hematopoietic system (e.g., aplastic anemia), gastrointestinal system (e.g., nausea and vomiting) and neurovascular system (e.g., dizziness);    (2) chronic radiation syndrome (CRS), which is caused when the entire human body is exposed to ionizing radiation over a long period of time (e.g., several months or years), and whose symptoms include skin atrophy, cataracts, sterility, etc.; and    (3) injury caused by radiation therapy, which results when a specific part of a human subject is exposed to ionizing radiation, and whose symptoms include anorexia, lassitude, diarrhea, erythema, desquamation, bowel stenosis, necrosis of bone, fibrosis of lung, etc.
The radioprotective agents used clinically to alleviate radiation injury include: free radical scavengers (e.g., catalase), antioxidants (e.g., vitamin E), cytokines (e.g., interleukin-1), thiols (e.g., Amifostine) and steroids (e.g., 5-Androstenediol). Among these, Amifostine is the only radioprotective agent approved by the Food and Drug Administration (FDA). Although Amifostine is effective in protecting tissues against radiation injury, it also leads to severe side effects (e.g., nausea, vomiting and hypotension) in users. Therefore, researchers in this field have attempted to find active components within traditional Chinese medicine that can be used to treat and/or prevent radiation injury.
Hippophae rhamnoides L. (trivial name: sea-buckthorn; SHA JI in pinyin) is a deciduous shrub which belongs to the genus Hippophae and family Elaeagnaceae. Hippophae rhamnoides L. can be found in the Chinese provinces: Hebei, Shanxi, Shaanxi, Gansu, Qinghai, etc. Studies have indicated that Hippophae rhamnoides L. can be used to treat liver injuries, gastric ulcers, tumors, etc. (Cheng T. J. (1992), Zhonghua Yu Fang Yi Xue Za Zhi, 26:227-229; Xing J. et al. (2002), Fitoterapia, 73:644-650; Yasukawa K. et al. (2009), Fitoterapia, 80:164-167).
Research regarding radioprotection of Hippophae rhamnoides L. extracts has begun to attract attention in recent years. For example, in Chawla R. et al. (2007), J. Med. Food, 10:101-109, the dried and powdered berries of Hippophae rhamnoides L. were extracted with ethanol, followed by filtration and concentration. The viscous extract thus obtained was washed with hot hexane and ether to remove nonpolar fractions. The remaining extract was passed over a bed of silica gel using a mixture of ethyl acetate and methanol [40:60 (v/v)] as an eluent. The partially purified fractions were again passed through a column containing a weakly polar polymeric adsorbent resin, followed by elution using 20-80% ethanol in water so as to obtain fractionated extracts. The fractionated extracts were pooled and concentrated to obtain a flavonoid-rich fraction, and designated REC-1001. High performance liquid chromatography (HPLC) revealed the presence of kaempferol, isorhamnetin and quercetin in REC-1001. REC-1001 was further subjected to bioactivity analysis, and results proved that REC-1001 possesses antioxidant, free radical scavenging and radioprotective activities. Therefore, Chawla R. et al. deem that kaempferol, isorhamnetin and quercetin in REC-1001 confer REC-1001 with the above-mentioned bioactivities, and REC-1001 may be a safe and effective antioxidant nutraceutical product.
Isorhamnetin is a flavonoid present in medicinal plants (e.g., Persicaria thunbergii, Hippophae rhamnoides L. and Brassica campestris L.), and has the following formula (I):

It is known that isorhamnetin is effective in preventing endothelial cell injury, treating enteritis, and possesses anti-tumor and anti-adipogenesis properties (Bao M. and Lou Y. (2006), Eur. J. Pharmacol., 547:22-30; Teng B. S. et al. (2006), Pharmacol. Res., 54:186-194; Lee J. et al. (2010), Life Sci., 86:416-423; CN 103462957 A).
Isorhamnetin glycosides are derivatives of isorhamnetin. Common isorhamnetin glycosides include isorhamnetin-3-O-β-D-glucoside, isorhamnetin-3-O-β-D-rutinoside, isorhamnetin-3-O-galactoside, etc. Isorhamnetin-3-O-β-D-glucoside can be isolated from Hippophae rhamnoides L., Cochlospermum religiosum and Brassica campestris L. Isorhamnetin-3-O-β-D-glucoside is a flavonoidal glucoside, and it has the following formula (II):

Studies have indicated that isorhamnetin-3-O-β-D-glucoside is effective in treating tumor and diabetes, preventing liver injury and retarding selenite-induced cataract (CN 1518986 A; Lee Y. S. et al. (2005), Biol. Pharm Bull., 28:916-918; Igarashi K. et al. (2008), Biosci. Biotechnol. Biochem., 72:856-860; Devi V. G. et al. (2010), Toxicol In Vitro., 24:1662-1669).
As far as the inventors are aware, there have been no documents or prior art patents which disclose that isorhamnetin-3-O-β-D-glucoside can be utilized in the alleviation of radiation injury.